With regard to a magnetic head for a hard disc device, recently, for use with an inductive head at the writing side, a composite magnetic head (which hereinafter will be called a composite head) in which such as an MR head, GMR head and TMR head (which hereinafter will be represented as an MR head) is used at the reading side.
Recording density of a hard disc has been steadily improved such as to a few ten gigabyte/inch. In addition, installations of an HDD to home electric appliances with digital technologies accelerate the improvement. For this reason, a demand for magnetic head assemblies, which are indispensable for the installation of the HDD, is increasing rapidly.
The magnetic head assembly is usually constituted by such as a head slider, which installs a composite head having an MR head and a suspension spring for supporting the same, the head slider is fixed to a head actuator such as a voice coil motor via the suspension spring.
The composite head in the head slider is formed integrally with the slider through a thin film process. Different from the inductive head at the recording side, in the MR head, a variety of defects such as a resistance defect, an insulation defect with a magnetic shield and an electric characteristic defect are likely caused in comparison with other types of heads. Therefore, an electrical characteristic testing of the magnetic heads including such as MR heads is performed under a condition a of slider single body (head slider).
For a defect testing of a head slider (in a slider single body condition) prior to assembling into a head assembly, a testing apparatus, which measures a reproducing characteristic of an MR head by applying externally a DC magnetic field to the MR head is disclosed and known from JP-A-2000-260012.
Further, for testing under assembled condition as a head assembly, a testing of an MR head in which while applying such as an AC recording magnetic field to the MR head and applying externally such as a DC magnetic field thereto, an output voltage waveform is obtained from the MR head to determine the characteristic is disclosed and known from JP-A-10-124828.
The size of a head slider is at most 1 mm square or less and on the side face at the trailing edge of the head slider four or six connection terminals for a composite head are provided. The height of the head slider is about 0.5 mm, and usually the magnetic head is provided at the trailing edge of the head slider together with the connection terminals. During testing of the head slider (in a slider single body condition), if the connection terminals of four or six are not surely contacted with a probe, the testing cannot be performed successfully.
Moreover, when measuring a reproducing characteristic of an MR head under a condition of applying a DC magnetic field externally, in these sorts of testing apparatus, an external magnetic field generating device has to be disposed extremely close to the head slider. Further, the measurement items have to cover a wide range of testing such as a quasi-magnetic response characteristic test (QUASI-TEST) of the MR head and a hysteresis characteristic test as a magnetic material. In addition, the testing has to be completed in a short time (about one second) for one piece of head slider.
Therefore, in order to enhance the efficiency of the head slider testing, it is proposed to measure the electric characteristic of an MR head under a condition of a row bar in a process before cutting out into head slider single bodies (chips). A row bar is a long and narrow rectangular plate block cut out from a wafer wherein head sliders are aligned along a length of about 3 cm˜5 cm. The head sliders of about 40 pieces˜60 pieces are aligned and formed in one row along a row direction of a wafer and what is cut out from the wafer is the row bar.
Row bars of about 20˜30 pieces are usually collected and aligned in a perpendicular manner with a predetermined interval and are accommodated in a tray. It is studied to take up each of the row bars one by one from the tray with a handling robot, to transfer the same to a testing stage and to test the same. The row bars are roughly positioned, when being accommodated in the tray, and are accommodated therein with a small gap from the surrounding wall faces of the tray. Because of such positioning, dispersion of row bar positioning in the tray is caused in a range of about ±0.5 mm.
For this reason, in order to contact connection terminals of a row bar in a shape of a long and narrow rectangular plate block with a probe, the longitudinal direction of the row bar where the connection terminals are aligned has to be highly accurately positioned at the testing stage. One of methods conceived for that is to butt one of the latitudinal side faces of the row bar (plate block) to a reference plane provided in the longitudinal direction. In that, a positioning processing through butting is conceived wherein after positioning through this butting the row bar is transferred to the testing stage. For this purpose, a prestage for the positioning has to be provided. However, when performing such positioning through butting, it is difficult to perform the positioning processing through butting while holding a long and narrow row bar having a length of a few cm, moreover, since the positioning is performed during the processing, the transferring time of the row bar to the testing stage is prolonged, which causes a problem. Of course, positioning processings other than the positioning through butting are conceived, however, such processings are considered to require more time than that of the positioning through butting.
Further, the technology in which a head slider is set at a testing stage after performing a positioning processing through butting and a testing of the head slider is performed was invented by the present inventors and is already known as JP-A-2006-351087 and JP-A-2007-26552. Still further, a technology in which a row bar is set at a testing stage and a testing of the row bar is performed was invented by the present inventors and is already known as JP-A-2007-48425 (which corresponds to US Publication No. 2007-0013369-A1).